The present invention relates to a failure restoring system of a transmission network and, more particularly, to a failure restoring system for forming an alternate route between logical channel nodes by self-distributed processing.
In a logical channel node failure restoring system of a conventional self-distributed network failure restoring system, in response to failure detection on the downstream side of a failure, a unit on the downstream side of the failed channel sends a packet for searching an alternate route to all connected transmission lines. A relay unit adds information such as the No. of its own node and the number of passed hops to the alternate route search packet and similarly sends the alternate route search packet to all the connected transmission lines. When a node on the upstream side of the failure, i.e., a final connection destination receives the alternate route search packet, the node checks in a reception order whether required alternate channel conditions are satisfied. If a corresponding channel is present, the node sends a connection request packet to the channel to perform failure restoration.
In the conventional self-distributed logical channel node failure restoring system, however, the alternate route search packet passed through various paths reaches a corresponding logical node having a channel to be restored. Therefore, since a channel which satisfies predetermined conditions (e.g., the number of hops) is selected as an alternate route, an optimal alternate route is not sometimes selected.